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>1.8. Buying a Second Hand Laptop</H1
><P
>&#13; Some recommendations to check a used laptop, before buying it:
</P
><P
>&#13;
<P
></P
><OL
TYPE="1"
><LI
><P
>&#13; Review the surface of the case for visible damages.
</P
></LI
><LI
><P
>&#13; Check the display for pixel faults. Maybe it's useful to take a
magnifying glass therefore. By the way: There is a standard for pixel
faults etc. ISO 13406-2.
</P
></LI
><LI
><P
>&#13; Do an IO stress-test, .e.g. with the tool <B
CLASS="command"
>bonnie</B
>.
</P
></LI
><LI
><P
>&#13; You may use <B
CLASS="command"
>memtest</B
> and <B
CLASS="command"
>crashme</B
> to
achieve a memory test.
</P
></LI
><LI
><P
>&#13; Do a CPU stress test, e.g. with the command <B
CLASS="command"
>md5sum /dev/urandom</B
> or by
compiling a kernel.
</P
></LI
><LI
><P
>&#13; Check the floppy drive by formatting a floppy.
</P
></LI
><LI
><P
>&#13; Check the CD/DVD drive by reading and writing a CD/DVD.
</P
></LI
><LI
><P
>&#13; To check the battery seems difficult, because it needs some time: one
charge and one work cycle. You may use <B
CLASS="command"
>battery-stats</B
>
to do so, but note this tool only offer APM support, it
is not available with ACPI support yet.
</P
></LI
><LI
><P
>&#13; To check the surface of the harddisk you may take
<B
CLASS="command"
>e2fsck</B
>. There is also a Linux tool
<B
CLASS="command"
>dosfsck</B
> or the other <B
CLASS="command"
>fsck</B
> tools.
</P
></LI
><LI
><P
>&#13; To test the entire disk (non-destructively), time it for performance,
and determine its size, as root do:
<B
CLASS="command"
>time dd if=/dev/hda of=/dev/null bs=1024k</B
> .
</P
></LI
><LI
><P
>&#13; Check whether the machine seems to be stolen. I have provided a
<A
HREF="http://tuxmobil.org/stolen_laptops.html"
TARGET="_top"
>survey of databases for stolen laptops</A
>.
</P
></LI
></OL
>
</P
><P
>&#13; AFAIK there is no Linux tool like the DOS tools CHECK-IT,
DR. HARD, SYSDIAG and others. These tools include many of the
tests in one integrated suite. One of the best in my humble
opinion is the tool
<A
HREF="http://members.datafast.net.au/~dft0802/"
TARGET="_top"
>PC Diagnostics 95</A
>
made by Craig Hart. Despite the 95 in its name it's plain DOS, tiny (
76KB program and 199KB data) reliable and free. Unfortunately it
contains no check for the <SPAN
CLASS="trademark"
>IrDA</SPAN
>&reg; port.
</P
><P
>&#13; Please note this quotation from the disclaimer: "This program is written
with the target audience being a trained, experienced technician. It is
NOT designed to be used by those ignorant of computer servicing.
Displays are not <EM
>pretty</EM
> but functional. Information
is not explained since we are not trying to educate. This software
should be considered to be just like any other tool in a tech's toolbox.
It is to be applied with care, in the right situation, in order to find
answers to specific problems. If you are an end user who is less than
confident of dealing with computer hardware, this is probably not a
program for you."
</P
><P
>&#13; Laptop computers, unlike desktop machines, really do get used up.
<EM
>Lithium batteries</EM
> are good for no more than 400
recharge cycles, sometimes much fewer. <EM
>Keyboards</EM
>
wear out. <EM
><SPAN
CLASS="acronym"
>LCD</SPAN
> screen
backlighting</EM
> grows dim. <EM
>Mouse buttons</EM
>
fail. Worst of all, <EM
>connectors</EM
> get loose as a
result of vibration, causing intermittent failures (e.g. only when you
hit the &#60;Enter&#62; key). We have heard of a machine used on the table
in a train being shaken to unusability in one trip.
</P
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